Geoengineering Our Way Out of Global Warming

An increasing number of prominent climate scientists and environmentalists (e.g., here and here) are expressing concerns that the point of no return -- when even the most extreme measures to reduce greenhouse gas emissions will be inadequate to reverse many consequences of global warming -- is rapidly approaching.

Speculation on the exact nature of the consequences ranges from coastal cities being submerged under rising seas, more severe floods and droughts, longer and more extreme heat waves, food and water shortages that spark civil unrest, and the reversal of ocean currents leading (ironically) to an ice age, to name a few. Then there's the ultimate doomsday scenarios -- extinction of the human race, or merely the decline of civilization as we know it.

Some of the speculation is based on the latest peer-reviewed science and assessments by the Intergovernmental Panel on Climate Change. The more dramatic end-of-the-world predictions smell more of scaremongering to force policymakers to act, and act now, to reduce emissions of carbon dioxide and other greenhouse gases.

Some of those who believe the tipping point is near -- the point beyond which some impacts of climate change, be they catastrophic or less so, are inevitable -- are giving serious consideration to the idea of geoengineering, deliberate actions taken to slow or reverse global warming by either removing carbon dioxide from the atmosphere or by reducing the amount of sunlight reaching Earth. In other words, Plan B.

Keep reading for more on what geoengineering is all about...

The topic of geoengineering has gained enough traction that the U.S. National Academies is hosting a workshop on the subject this summer, and the UK's national academy of science is preparing a report on the feasibility of climate geoengineering. A recent article in the journal Foreign Affairs states that, "As climate change accelerates, policymakers may have to consider 'geoengineering' as an emergency strategy to cool the planet. Engineering the climate strikes most as a bad idea, but it is time to start taking it seriously." And an advisory group to the Defense Advanced Research Projects Agency recently convened a meeting to discuss geoengineering -- not withstanding concerns expressed by some that military involvement might lead to the use of climate geoengineering as a weapon.

Among the approaches being considered to reduce the solar radiation reaching the ground are firing plumes of fine dust or pumping sulfur dioxide into the atmosphere to deflect the sun's rays in a manner that mimics the cooling effects of volcanic eruptions, and deploying large arrays of land-based mirrors and/or launching mirrors into orbit around Earth (e.g., see here).

Among the schemes for removing carbon dioxide from the atmosphere is dumping tons of iron into the ocean. Iron is necessary for algae photosynthesis, a process that sucks carbon dioxide from the air but is relatively rare in the ocean. In principle, the iron would supercharge the growth of algae, which when it dies would sink to the ocean bottom carrying the carbon with it. A recent iron-fertilization experiment off the coast of Argentina indeed produced a massive algae bloom, but it turned out to be a different kind of algae than anticipated, and one that was quickly devoured by tiny shrimp and other sea life, leaving experts scratching their heads on what the experiment's results mean for iron fertilization as a strategy to sequester carbon. Another approach being discussed is creating plantations of fast-growing trees, which absorb carbon dioxide from the air and convert it into wood, then converting the wood into charcoal (by burning it in the absence of oxygen) and burying the charcoal to prevent the carbon from ever returning to the air.

I've written previously of smaller-scale weather (as opposed to climate) modification programs, including China's efforts to avoid rain during the 2008 Olympics and to induce drought-relieving snowfall by seeding clouds with silver iodide. As I indicated in those posts, neither the Chinese nor anyone else has demonstrated that such weather modification programs produce meaningful changes in overall precipitation patterns. For one thing, it's not possible to know for sure what might have occurred in the absence of cloud seeding. Additionally, it's extremely difficult, maybe impossible, to anticipate unintended consequences -- for example, a seeding-induced increase in precipitation in one place could result in less precipitation somewhere else. In such situations, the legalese of responsibility and liability becomes a major concern.

This classic illustration of the law of unintended consequences -- solving one problem but inadvertently creating another -- is likewise a concern when it comes to geoengineering the climate, but on a much larger scale. This includes addressing questions such as which nation or nongovernmental entity should decide whether the potential benefits outweigh the risks, and who is responsible for correcting (if possible) unintended consequences?

Aside: To the best of my knowledge there's been very little coverage of climate geoengineering and its implications in mainstream newspapers and TV news broadcasts. There are obviously many important issues and events to cover these days, but I'm surprised that geoengineering has not been judged more newsworthy given what's currently happening in the field.

See also our previous post highlighting a new documentary on geoengineering.

Steve - interesting story on a controversial subject. A couple of points:

It's not necessarily the fear of absolute catastrophe that is motivating many to call for geoengineering, since worst-case scenarios are high impact but low probability events. Instead, advocates for such plans tend to think that they are necessarily because of the long atmospheric lifetime of carbon dioxide, and the possibility that emissions reductions alone won't sufficiently reduce atmospheric concentrations of greenhouse gases.

In other words, it isn't that these people see climate change as being more severe than others, although some of them do, but rather that they view the solution differently.

Also, while geoengineering might sound fanciful to many readers, it's worth pointing out that through emissions of greenhouse gases, humans are already rigging the climate system (albeit in the wrong direction).

Also, another important consideration is that it's not known whether the possible consequences of global warming would occur gradually over century time scales or much more rapidly, perhaps over a decade or so if some possible "tipping point" is reached. If the latter, the lifetime of atmospheric CO2 becomes much less relevant.

skywatcher1,
what's your point with that link? are you saying that is evidence "in favor of" or "against" global warming theory?

mainstream GW theorists put those ~11yr cycles in their models. it is one of the reasons they think the last few years have not been record-breakers - and is related to the reason we hear from some that "global warming is over" (because we're not setting a new record every year...)

Great blog post. I would like to correct one thing: engineered sun dimming aerosol could be 10X more power and avoid some of side effects (like acidification or ozone depletion) of sulfite/sulfide particles. Just because volcanoes dim the sun with hydrogen sulfide doesn't mean we can't find a better substitute.

There is a simple and cheap way to cool the Earth down immediately: just add a little sun dimming aerosol to the upper atmosphere. It could be reversed quickly too, just by ceasing. Our pollution is already significantly dimming the sun accidentally and stopping 1-2 degrees C of warming, in what Dr James Lovelock calls a "Fool's Climate." We won't be able to stop ecosystem collapse and the routine failure of non-irrigated crops unless we resort to geoengineering.

"The alternative (to geoengineering) is the acceptance of a massive natural cull of humanity and a return to an Earth that freely regulates itself but in the hot state." --Dr James Lovelock, August 2008

Great blog post. I would like to correct one thing: engineered sun dimming aerosol could be 10X more power and avoid some of side effects (like acidification or ozone depletion) of sulfite/sulfide particles. Just because volcanoes dim the sun with hydrogen sulfide doesn't mean we can't find a better substitute.

There is a simple and cheap way to cool the Earth down immediately: just add a little sun dimming aerosol to the upper atmosphere. It could be reversed quickly too, just by ceasing. Our pollution is already significantly dimming the sun accidentally and stopping 1-2 degrees C of warming, in what Dr James Lovelock calls a "Fool's Climate." We won't be able to stop ecosystem collapse and the routine failure of non-irrigated crops unless we resort to geoengineering.

"The alternative (to geoengineering) is the acceptance of a massive natural cull of humanity and a return to an Earth that freely regulates itself but in the hot state." --Dr James Lovelock, August 2008

dobermantmacleod,
what do you mean by, "It could be reversed quickly too, just by ceasing."?

does the stuff just disperse off into space if it's put in the upper atmosphere? my big big big concern with any kind of geoengineering project is that we don't know what the **** we're doing. whatever we do has to be practically instantly "undone" if things start going bad. that's why in principle i don't like the idea of dumping something in the ocean. my "favorite" so far is the space mirror/reflector idea.

skywatcher1: I fully agree with you.....100% You are right on. In a couple of decades, just as you say, historians (and many scientists) are going to look back on the global-warming hysteria of today and wonder how we could ever have believed this stuff.....just as we now look back on the global-cooling "Ice-Age" forecast of the 1970s and see what nonsense that was, too.

There is big difference between gullibility and reasoned appraisal of state-of-the-art science based, quantifiable analysis of issues relevant anthropogenic global warming (AGW). Dismissing with total (100%) certainty that AGW is and will likely continue and have significant consequences is not rational, and hopefully will be recognized as such by open minded citizens and policy makers.

It's far more likely (but not totally certain) that those dismissing AGW out of hand will look back 20 years from now and wonder how wrong they were in being so unreasonable (but never admit,of course).